JP 2000-289376 A discloses a plastic-made binder which is used to bind loose-leaf papers on the market or documents punched by a multi-hole puncher. This binder is a one-piece molded product in which a large number of ½ ring portions are arranged at given intervals in two lines on both sides of a back part of the binder, and the back part of the binder itself is a hinge composed of two divided sections. With the back part between the two lines, one line of ½ ring portions respectively include spherical-shaped projections on the leading ends thereof, whereas the other line of ½ ring portions respectively include in the leading ends thereof holes respectively having shapes corresponding to their associated projections. When the spherical-shaped projections and holes are fitted with each other, the two lines of paired ½ ring portions are connected together, thereby binding the loose-leaf papers.
In the field of office automation equipment, there is known a kind of composite machine which includes a copying machine and a stapler incorporated in the copying machine and is capable of carrying out operations ranging from a copying operation to a binding operation. It may be more convenient to be able to provide an automatic binding processing machine which punches holes in copied papers and attaches a binder to the copied papers. It can be estimated that potential demand for such automatic binding processing machine must be large.
To realize this type of binding processing machine, means for handling a binder is an important element. For example, it is necessary for the binder to have a structure suitable for mechanically handling or carrying out binder operations such as binder feeding, holding and fitting operations. However, the binder disclosed in JP 2000-289376 A is structured on the assumption that it is mounted by hand into a binding processing machine but not on the assumption that it is handled mechanically. Thus, it is difficult to use this binder in a binding processing machine which does not require the manual operation.
In view of this, there has been proposed a binder having a structure which is suitable for use in the binding processing machine. For example, a binder disclosed in JP 2004-237578 A is structured such that, the back part of the binder is projected forwardly or toward the back surface of the binder and thus, when a number of binders are piled up on top of each other, the back part of one binder can be contacted with the front surface or back surface of the other binder. According to this structure, even when a large number of binders are piled up on top of each other, the individual binders can be piled up in such a manner they respectively can keep their initial shapes, whereby, when the binders are loaded into a cartridge provided in the binding processing machine, the smoothness of the feeding and mounting of the binders can be improved.
Also, a binder disclosed in JP 2004-237579 A is structured such that one or more recessed portions are formed on one of the front and back surfaces of the back part of the binder, and such that one or more projecting portions to be fitted and paired with the recessed portions are formed on the other surface, whereby a plurality of binders can be connected together while they are piled up on top of each other. This structure can facilitate the handling of the piled-up binders.
Further, a plastic-made binder disclosed in JP 2004-237580 A has a scarf joint structure in which, in the end portions of sectioned ring portions to be fitted and paired with each other, there are provided symmetrical steps extending in the radial direction thereof. Further, this binder includes a hook portion on one end thereof, and a catch portion to be fitted and paired with the hook portion on the other end thereof, thereby providing means for fitting its sectioned ring portions with each other. Therefore, this binder requires less power for fitting when compared with the structure of the binder disclosed in JP 2000-289376 A in which the spherical projections are fitted into the holes. Also, according to this binder, the structure of a die for molding it can be further simplified.
To enable the binding processing machine to carry out a binding processing operation, there are necessary means for holding a binder and a pusher or a press mechanism for folding and fitting the ring parts of the binder with each other. The means for holding the binder is almost unable to mount the binder while it holds the ring parts which are folded by the pusher or the like; and, therefore, the binder holding means actually holds the back part of the binder.
However, it is not easy to hold the narrow back part and maintain the binder in a proper orientation until the binding processing is completed. When the binder is rotated about the back part thereof and is thereby inclined from its regular orientation, the ring parts might not be inserted into punched holes formed in papers or the ring parts might not be fitted with each other properly.